Metathesis overview

In this chapter I will cover only well-defined or well-characterized compounds. Results will be included that have appeared since reviews in 1991 on alkylidene and metalacyclobutane complexes [41] and in 1993 on ring-opening metathesis polymerization [30], but an overview of prior results that are especially relevant to olefin metathesis in particular will also be included. (An excellent and comprehensive text also has been published recently [1].) The terms well-defined or well-characterized originally were meant to imply that the alkylidene complex is isolable and is essentially identical to that in a catalytic reaction except for the identity of the alkylidene. These terms have been watered down from time to time in the literature, even to the point where they are used to describe a catalyst that is formed from a well-characterized transition metal precursor complex, but whose identity actually is not known. In this article I... 

This review article offers an overview of stereo- and regioselective processes, developed in our laboratories, that are carried out in conjunction with various catalytic RCM reactions. As mentioned above, several reaction technologies involve stereoselective functionalization of the RCM products, and others were developed such that subsequent reactions effected by a metathesis catalyst promote the formation of the desired target molecules selectively and efficiently. 

Numerous catalysts and metathesis reactions have been reported and it is not possible to do justice to all authors, not even to those who have contributed to the development of the mechanistic proofs summarised above. In Figure 16.9 we have collected a schematic overview of the type of reactions that are usually distinguished in metathesis catalysis. 

These observations indicate that there is no sharp borderline between cyclopro-panating and metathesis-catalyzing carbene complexes. Fortunately the number of carbene complexes which mediate both cyclopropanation and alkene metathesis is rather small, and in the detailed overview given in the following sections it will become apparent that most carbene complexes are highly selective and thus valuable reagents for organic synthesis. 

For a previous brief overview of this Mo-catalyzed asymmetric olefin metathesis, see Hoveyda, AH, Schrock RR (2001) Chem Eur J 7 945... 

Amidocarbonylation aldehydes, 11, 512 enamides, 11, 514 overview, 11, 511-555 Amido complexes with bis-Cp titanium, 4, 579 Group 4, surface chemistry on oxides, 12, 515 Group 5, surface chemistry on oxides, 12, 524 with molybdenum mono-Cp, 5, 556 with mono-Cp titanium(IV) alkane elimination, 4, 446 amine elimination, 4, 442 characteristics, 4, 413 via dehalosilylation reactions, 4, 448 HCL elimination, 4, 446 metathesis reactions, 4, 438 miscellaneous reactions, 4, 448 properties, 4, 437... 

CRM, see Cyclopentadienyl ring metathesis Cross-coupling polymerization miscellaneous reactions, 11, 678 overview, 11, 653-690... 

P2N2 dianionic macrocycle, 1, 69 pyridinophane macrocycles, 1, 69 Macrolides, via ring-closing metathesis, 11, 239 Macromolecular materials overview, 12, 295-411 polymers (, see Polymers)... 

Platinum complexes (continued) with aryls, thallium adducts, 3, 399 with bis(alkynyl), NLO properties, 12, 125 with bisalkynyl copper complexes, 2, 182-186 with bis(3,5-dichloro-2,4,6-trifluorophenyl), 8, 483 and C-F bond activation, 1, 743 in C-H bond alkenylations, 10, 225 in C-H bond electrophilic activation studies, 1, 707 with chromium, 5, 312 with copper, 2, 168 cyclometallated, for OLEDs, 12, 145 in diyne carbometallations, 10, 351-352 in ene-yne metathesis, 11, 273 in enyne skeletal reorganization, 11, 289 heteronuclear Pt isocyanides, 8, 431 inside metallodendrimers, 12, 400 kinetic studies, 1, 531 on metallodendrimer surfaces, 12, 391 mononuclear Pt(II) isocyanides, 8, 428 mononuclear Pt(0) isocyanides, 8, 424 overview, 8, 405-444 d -cP oxidative addition, PHIP, 1, 436 polynuclear Pt isocyanides, 8, 431 polynuclear Pt(0) isocyanides, 8, 425 Pt(I) isocyanides, 8, 425 Pt(IV) isocyanides, 8, 430... 

The wide range covered by nearly forty contributions ensures a concise overview of the latest developments in the field, w hethcr they be new methods of C-C bond formation or race-mization, asymmetric phase-transfer catalysis or stereoselective metathesis reactions, solid phase reactions or particularly elegant syntheses of challenging natural products. 

This work consists of an overview of the major developments in the alkene metathesis reaction since 1997. In view of the breadth of the subject area and the rapid pace of advancement in the field in recent years, this review is not intended to serve as a comprehensive survey, but rather as an account of how the development of novel catalyst systems has made a dramatic impact on the reaction in terms of scope and efficiency/selectivity. 

The enyne metathesis has been recently reviewed [91-93]. For an overview of the enyne metathesis involving organosilicon compounds see Ref. [6]. 

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